title: Structural determinants for geometry and information decoding of tRNA by T box leader RNA.
abstract: T box riboswitches are cis-acting RNA elements that bind to tRNA and sense its aminoacylation state to influence gene expression. Here, we present the 3.2 Å resolution X-ray crystal structures of the T box Stem I-tRNA complex and tRNA, in isolation. T box Stem I forms an arched conformation with extensive intermolecular contacts to two key points of tRNA, the anticodon and D/T-loops. Free and complexed tRNA exist in significantly different conformations, with the contacts stabilizing flexible D/T-loops and a rearrangement of the D-loop. Using a designed T box RNA/tRNA system, we demonstrate that the T box riboswitch monitors the length and orientation of two essential contacts. Length or orientation mismatches engineered into the T box riboswitch and tRNA disrupt the complex, whereas simultaneous insertion of full helical turns realigns the interfaces and restores interaction between artificially elongated T box riboswitch and tRNA molecules.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14850, USA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Grigg
authors.forename: Ailong
authors.initials: A
authors.lastname: Ke
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D018360:Crystallography, X-Ray; D056506:Geobacillus / Q000235:genetics*; D006860:Hydrogen Bonding; D055029:Inverted Repeat Sequences; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics; D012343:RNA, Transfer / Q000737:chemistry* / Q000235:genetics
chemical_list: D012329:RNA, Bacterial; D012343:RNA, Transfer